This invention relates generally to variable resistance devices and methods and, more particularly, to devices and methods which employ resistive resilient materials including resistive rubber materials for providing variable resistance.
Variable resistance devices have been used in many applications including sensors, switches, and transducers. A potentiometer is a simple example of a variable resistance device which has a fixed linear resistance element extending between two end terminals and a slider which is keyed to an input terminal and makes movable contact over the resistance element. The resistance or voltage (assuming constant voltage across the two end terminals) measured across the input terminal and a first one of the two end terminals is proportional to the distance between the first end terminal and the contact point on the resistance element.
Resistive elastomers or resistive rubber materials have been used as resistance elements including variable resistance devices. The terms “resistive rubber” and “resistive rubber material”, as used herein, refer to an elastomeric or rubber material which is interspersed with electrically conductive materials including, for example, carbon black or metallic powder. Heretofore, the use of resistive rubber in variable resistance devices has been limited to relatively simple and specific applications. For instance, some have only exploited the variable resistance characteristics of a resistive rubber caused by deformation such as stretching and compression. There is a need for variable resistance devices and methods which utilize more fully the resistive characteristics of resistive rubber materials.